Nominatim

Provides worldwide forward / reverse geocoding

Nominatim is OpenStreetMap's free geocoding service providing forward geocoding (address to coordinates) and reverse geocoding (coordinates to address). It searches the entire OpenStreetMap database, covering the globe with community-maintained data. No API key needed for the public instance. For OpenClaw agents, Nominatim is the go-to free geocoding API. Your agent can convert addresses to coordinates for weather lookups, reverse-geocode GPS coordinates to human-readable locations, or search for places by name. It's completely free, but the public instance has strict usage policies.

Tags: maps, geolocation

Category: Geocoding

Use Cases

  • Convert place names to coordinates for weather or air quality API lookups
  • Reverse geocode GPS coordinates from phone location to readable addresses
  • Search for places by name to provide location context in agent responses

Tips

  • Always set a descriptive User-Agent header (e.g., 'OpenClaw-Agent/1.0')
  • Use structured queries (street, city, country params) for more accurate results
  • Cache geocoding results — addresses don't move, so results are long-lived

Known Issues & Gotchas

  • MUST include a User-Agent header — requests without one are blocked
  • Strict 1 request/second rate limit on the public instance — no bursting
  • Results are OSM data — address formats vary by country and may differ from Google

Frequently Asked Questions

Can I use Nominatim without an API key?

Yes. The public instance requires no authentication. However, you MUST include a valid User-Agent header or your requests will be blocked. The usage policy also requires max 1 request/second.

Is 1 request/second sufficient?

For agent use, yes. You're geocoding addresses occasionally, not running batch jobs. If you need bulk geocoding, self-host Nominatim or use a commercial service like OpenCage.

How does data quality compare to Google Maps?

OpenStreetMap data is excellent in Europe and major cities worldwide. In some rural areas or developing countries, Google Maps may have better coverage. For most agent use cases, Nominatim is more than sufficient.